For accomplishing the process of feeding sheets, a common sheet feeder design utilizes a support member, typically a tray or cassette containing a supply of sheets therein, which is biased toward a feeding member such as a friction-type roller. With this type of sheet feeder, the existence of a deficient supply of sheets supported by the support member can be detected by detecting the diminished weight of the depleted supply of sheets against the biasing force urging the sheets toward the friction roller (see e.g., U.S. Pat. No. 3,949,979. The desirability of this type of sheet feeder, however, is limited by certain problems described within a co-pending U.S. patent application for a Sheet Feeder filed concurrently and designated by Ser. No. 161,741, incorporated herein by reference. In light of these teachings it is desirable to have a device for detecting a depleted sheet supply, which does not depend upon the decreasing weight of the depleting supply of sheets. It is also desirable to have a device capable of providing an early warning of the depleting supply as well as an indication that the supply has been depleted. Finally, it is desirable to have a device which can easily be reset and which does not interfere with or make more difficult the process of replenishing the supply of sheets within the feeder.